Question

18. How many ATP can be produced by the complete oxidation of each propionyl-CoA product of fatty acid oxidation? Compare this to the ATP yield for each acetyl-CoA.

Answer 1

The energy yields from the oxidation of fatty acids with either odd or even number of carbon atoms. It has to be remembered that ATPs are consumed in the thiokinase reactions and that ATP results from the oxidation of both NADH and FADH2 originating in propionyl-coA oxidation and acetyl-coA oxidation in the TCA cycle.

The activation process uses 1 ATP but yields AMP ppi equivalent to 2 ATP molecules. Fatty acids with odd number of carbon atoms require an extra ATP in the propionyl-coA oxidation. The GTP produced in this reaction is counted as a ATP. To obtain the net energy yields it is important to calculate the toal ATP produced and the total ATP consumed. The propionyl-coA undergoes oxidation reactions in the TCA cycle to produce 6 ATP

Fatty acid containing 16 carbons in oxidation reactions produces total 129 ATP. There is anapleoretic fate of succinyl coA which when goes into citric acid cycle generates oxaloacetate. That means reactions will be like GTP+1FADH2+1NADH=1+2+3=6 ATP. And each acetyl-coA yields 12 ATP when getting oxidized in the citric acid cycle.